Which of the following is a TYPE of MALWARE that encrypts files and demands payment for the decryption key?

1. RANSOMWARE: malicious software that encrypts a victim's files and demands a ransom (typically cryptocurrency) for the decryption key. 2. Notable examples: WannaCry (2017), Petya, Ryuk, LockBit, BlackCat. 3. Mitigations: regular OFFLINE backups, patch management, MFA on remote access, email filtering, user training. 4. CRITICAL: never pay the ransom — funds criminal operations and offers no guarantee of recovery. 5. Other options: ADWARE shows unwanted ads; WORM self-propagates across networks; LOGIC BOMB triggers on a condition. _Source: NIST CSF DE.CM-4 (Malicious code is detected) + industry malware taxonomy._